We have previously reported increased relative cerebral blood flow (rCBF) in the left globus pallidus of neuroleptic-naive schizophrenics. We have demonstrated that regional oxygen metabolism (rCMR02) is also increased in the left globus pallidus (15) and have replicated the rCBF finding in an additional 12 neuroleptic-naive patients and 20 controls. It is thought that increased rCBF and rCMR02 in the left globus pallidus reflect either increased number or increased activity of neurons projecting to the globus pallidus. We have proposed a model of left striato-pallidal hyperactivity in schizophrenia to account for the left globus pallidus finding and other behavioral evidence for right-side hemineglect-like phenomena. This model predicts that neuroleptic treatment will be associated with a relative decrease in rCBF and rCMR02 in the left globus pallidus. We also expect that neuroleptic treatment will result in a reduction of frontal flow and metabolism.